Testing unit for wire sparkers



June 6, 1950 J. L. ENTWVISTLE TESTING UNIT FOR WIRE SPARKERS 3 Sheets-Sheet 1 Filed March 19, 1945 n22 CON ".22 0

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TESTIN UNIT FOR WIRE SPARKERS Filed March '19, 1945 s Sheets-Sheet s 2l-25 are closed and 20 is open, giving a total of 575 micro-micro-farads of series capacitance in the testing circuit, but will be tripped when switch 20 is closed.

amount of series capacitance in the circuit, usually 150 micro-micro-farads for high sensitivity sparkers when testing at 6,000 volts. The synchronizing switch 30 which insures simultaneous energization of motor and sparker supply is then turned on and the motor push-button 3| is actuated. This will close the circuit of motor I and, by holding the push-button -3| down until the timer arm passes the needle point and then immediately releasing, one will notice a spark jumping the gap and the usual indicator lamp (not shown) in the sparker itself will flash if the fault relay operates. The lamp in the sparker is customarily connected to contacts of relays 4 and 4'. If no spark is seen, then the button 3| should be pressed again and held down for two circuit of the portion of the testing unit used to test the sparker for voltages to which it may be 9 subjected is shown. Ground binding post [9 is common to both portions of the testing unit, as indicated by line 34. When it is desir d to test the voltage of the sparker rather than the sensitivity of relays 4 and '4', line 35 and plug iii are connected to binding post 33 and plug I'E disconnected from binding post t8. This portion of the testing unit is equipped with an electrostatic voltmeter 25 and a voltage divider 21 which allows testing of the sparker voltages up to 20,000 volts. The arm 28 of the voltage divider is connected with the electrostatic voltmeter 26 and it has three scales of 5, 10 and 20,000 volts obtainable, respectively, in the three positions of the arm. In order to prevent damage to the meter 26, the arm should always be left in the kv.

position and a reading should always be taken in this position before changing to a lower range on the Voltage divider. The sparker should always be turned offwhen changing the adjustment of the voltage divider range.

The speed of response and sensitivity tests should be carried'out at voltages that do not exceed 10 kv. because this is the rated limit of the series condensers. The usual testing voltage is 6 kv.

The unit should be placed close to the sparker,

preferably on the high tension side. First, the current supply to the sparker is disconnected and the testing unit is connected to the current supply by plugging in the current mains at 3. The sparker is then connected to the testing unit through the receptacle 2. Next, the ground and test cords are connected to the testing unit. The cords are indicated in Fig. 1 by It and H, which can be plugged into the binding posts l8 and IS. A timing strip 5 of the proper width is selected, and needle 8 is adjusted. The gap between 8 and 5 should be .2" for testing at 6,000 volts and .1" for testing at 3,000 volts. The timer arm 6 is then moved away from the needle about an inch in a counter-clockwise direction.

Sparker switch 29, synchronizing switch 30 and motor push-button 3| are open.

First, the-usual sparker control switch (not shown) is turned on, and then sparker switch 29, to energize the sparker. Indicator lamp 32, bridged across the receptacle 2, will new light showing that the sparker isbeing energized. The sparker test voltage is adjusted by a conventional voltage regulator (not shown) on the sparker to 6,000 or 3,000 volts, depending whether high or low voltage sparkers are used. and the sparker switch 29 is turned oiT.

Next, certain ones 'of the condenser switches 2l-25, are closed so as to introduce the proper or three revolutions of the timer 5.

If still no spark is noticed, then the needle 8 should be brought closer to the timer 5 and the process repeated.

If a spark is noted but the fault relay 4 fails to respond, then this indicates that the sparker fault location circuit is either not sensitive enough Or too slow to operate under test conditions.

To determine the sensitivity and the speed at which the fault relay circuit will operate, these tests should be repeated, using first a narrow timer strip 5, then a wider one and finally the Widest strip 5 provided. If the fault relay 4 still fails to respond, then the tests should be repeated, using more and more series capacitance each time, until the relay operates. When a series capacitance is reached at which the fault relay operates then, using this capacitance, the tests should be continued, using shorter and shorter time intervals until the relay fails to operate.

For voltage testing, the unit is connected to the current supply and the sparker as outlined above. Plug i6 is inserted into binding post 33, and plug l6 disconnected from binding post l8. The voltage regulator (not shown) on the sparker is a device which determines the amount of voltage to be applied by the sparker when testing a wire, etc., and must be in its lowest position and the synchronizing switch 30 must be open. The voltage divider arm 28 should be moved into the 20 kv. position and the sparker switch 29 closed. The voltage divider should not be changed while power is on the sparker.

The voltage on the sparker is then slowly raised to avalue which it is desired to check. The usual procedure is to check the highest value first and then successively lower values. When the voltage is less than 10 kv. then the arm 28 should be moved to the 10 kv. position and, when it is below 5 kv., then to the 5 kv. position.

The plan view of the testing unit (Fig. 2) and the end view of the box of the testing unit show how arm 28 of voltage divider 21 may be moved into three different positions, depending upon the voltage for which the sparker is being tested. Fig. 3 also shows how switches 2l-25 may be operated to vary the capacitance of the circuit as well as the location of the timer with respect to the needle. Figs. 2 and 3 enable one to see how compact and portable the testing unit is.

It will be obvious to those skilled in the art that in addition to' the tests above described, there may be other tests to which the sparker must be causing a predetermined current to how for a predetermined length of time are adjusted to oer-,-

tain standards, and then the fault-detecting means, such as one or more relays like 4, in the sparker are adjusted until it or they respond to such predetermined standard current.

The potentialeindicating means including the voltmeter 26 and switch 21 may be omitted from the testing device and constructed as a separate unit, or its function may be performed by a separate metering device.

What I claim'is:

1. An apparatus for testing fault detecting reindication that the relay operates.

2. The device according to claim 1, and means for varying the length of timewhile said arm forms a spark gap with the needlenduring each rotation, whereby the speed of response of said relay may be tested.

JAMES L. ENTWISTLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 734,369 Rodde July 21, 1903 1,350,334 Radtke Aug. 24, 1920 1,543,277 Courtier June 23, 1925 1,559,161 Courtier Oct. 27, 1925 1,971,196 McNarry Aug. 21, 1934 1,974,275 Janovitch Sept. 18, 1934 2,043,528 Davis June 9, 1936 2,087,783 Savage July 20, 1937 2,400,472 Strickland May 14, 1946 

